Determination of elastic moduli at high temperatures for uranium-vanadium alloy and pure plutonium by an ultrasonic method

Using a contact delay-line ultrasonic device, we measured the elastic proper-ties particularly the shear modulus mu of pure plutonium and uranium-vanadium alloy from ambient temperature to 900 K. Several allotropes of these materials have been detected in the explored temperature range. For plutonium metal, measurements reveal a collapse of mu(T) of about 50% for the alpha -> beta phase change. and a small increase of 0.2% for the beta -> gamma phase change. For uranium-vanadium alloy, we observe a monotonic decrease of about 50% of mu(T) for the a phase change. In order to include the phase transition to describe the variation of mu(T), a model has been proposed and applied. (c) 2006 Elsevier B.V. All rights reserved.